A large-diameter polyphenylsulfone monofilament and a method of making the same

Abstract

This invention provides a method for preparing large-diameter polyphenylsulfone (PPS) monofilaments, comprising the following steps: mixing PPS and a lubricant and then performing melt extrusion to obtain a melt; extruding the melt through a spinneret to obtain nascent monofilaments; sequentially subjecting the nascent monofilaments to oil bath cooling, drawing, and winding to obtain cooled and shaped nascent monofilaments; and sequentially subjecting the cooled and shaped nascent monofilaments to slow drawing and heat setting to obtain large-diameter PPS monofilaments; the slow drawing speed is 3–5 m / min. The addition of a lubricant in this invention improves the flowability and extrusion stability of PPS, preventing melt fracture during extrusion. The subsequent oil bath cooling improves the surface smoothness of the cooled nascent monofilaments, which is beneficial for subsequent drawing. The slow drawing speed allows for slow cold drawing of the nascent monofilaments, which not only enables molecular chain orientation but also prevents filament breakage, thereby obtaining large-diameter PPS monofilaments.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a large-diameter polyphenylsulfone monofilament and its preparation method. Background Technology

[0002] Polyphenylsulfone (PPSU) is composed of aromatic groups (phenylene) linked with sulfone and ether groups. At the same time, the "bridging" groups between the sulfone and ether groups also give PPSU some special performance characteristics, including hydrolytic stability, thermal oxidation stability, high operating temperature, and ductility.

[0003] Currently, the application of PPSU both domestically and internationally is limited to plastics of various shapes. PPSU has high melt viscosity and poor flowability; inadequate process control can easily lead to melt fracture, making spinning difficult. There are no reports of commercially produced PPSU monofilaments. Therefore, how to prepare polyphenylsulfone monofilaments has become a pressing technical challenge in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a large-diameter polyphenylsulfone monofilament and its preparation method. The melt-process provided by this invention can prepare large-diameter polyphenylsulfone monofilaments.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing large-diameter polyphenylsulfone monofilaments, comprising the following steps:

[0007] (1) Polyphenylsulfone and lubricant are mixed and then melt-extruded to obtain a melt;

[0008] (2) The melt obtained in step (1) is extruded through a spinneret to obtain a nascent monofilament;

[0009] (3) The nascent monofilaments obtained in step (2) are sequentially subjected to oil bath cooling, traction and winding to obtain cooled and shaped nascent monofilaments;

[0010] (4) The nascent monofilaments obtained in step (3) are subjected to slow stretching and heat setting in sequence to obtain large-diameter polyphenylsulfone monofilaments; the slow stretching speed is 3 to 5 m / min.

[0011] Preferably, in step (1), the melt index of polyphenylsulfone at 360°C and 5kg is 20-25g / 10min.

[0012] Preferably, the mass of the lubricant in step (1) is 0.05 to 0.1% of the mass of polyphenylsulfone.

[0013] Preferably, the temperature of melt extrusion in step (1) is 360-380°C.

[0014] Preferably, in step (1), the screw pressure during melt extrusion is 8–12 MPa, and the screw rotation speed is 30–50 r / min.

[0015] Preferably, the temperature of the oil bath cooling in step (3) is 40-50°C, and the oil bath cooling time is 5-10 seconds.

[0016] Preferably, the medium for oil bath cooling in step (3) is any one of silicone oil, triethylene glycol, and glycerin.

[0017] Preferably, the speed of slow stretching in step (4) is 1.5 to 1.7 times.

[0018] Preferably, the heat setting temperature in step (4) does not exceed 220°C, and the heat setting time is 50–80 seconds.

[0019] The present invention also provides a large-diameter polyphenylsulfone monofilament prepared by the preparation method described in the above technical solution.

[0020] This invention provides a method for preparing large-diameter polyphenylsulfone (PPS) monofilaments, comprising the following steps: mixing PPS and a lubricant and then performing melt extrusion to obtain a melt; extruding the melt through a spinneret to obtain nascent monofilaments; sequentially subjecting the nascent monofilaments to oil bath cooling, drawing, and winding to obtain cooled and shaped nascent monofilaments; and sequentially subjecting the cooled and shaped nascent monofilaments to slow drawing and heat setting to obtain large-diameter PPS monofilaments; the slow drawing speed is 3–5 m / min. The addition of a lubricant in this invention improves the flowability and extrusion stability of PPS, preventing melt fracture during extrusion. The subsequent oil bath cooling improves the surface smoothness of the cooled nascent monofilaments, which is beneficial for subsequent drawing. The slow drawing speed allows for slow cold drawing of the nascent monofilaments, which not only enables molecular chain orientation but also prevents filament breakage, thereby obtaining large-diameter PPS monofilaments. Experimental results show that the preparation method provided by the present invention can obtain polyphenylsulfone monofilaments with a diameter of 0.08-1.2 mm, a strength of 1.2-1.5 cN / dtex, and an elongation at break of 20-30%. Detailed Implementation

[0021] This invention provides a method for preparing large-diameter polyphenylsulfone monofilaments, comprising the following steps:

[0022] (1) Polyphenylsulfone and lubricant are mixed and then melt-extruded to obtain a melt;

[0023] (2) The melt obtained in step (1) is extruded through a spinneret to obtain a nascent monofilament;

[0024] (3) The nascent monofilaments obtained in step (2) are sequentially subjected to oil bath cooling, traction and winding to obtain cooled and shaped nascent monofilaments;

[0025] (4) The nascent monofilaments obtained in step (3) are subjected to slow stretching and heat setting in sequence to obtain large-diameter polyphenylsulfone monofilaments; the slow stretching speed is 3 to 5 m / min.

[0026] Unless otherwise stated, the present invention does not have any special limitations on the source of the above-mentioned raw materials, and commercially available products or well-known preparation methods known to those skilled in the art can be used for preparation.

[0027] This invention involves mixing polyphenylsulfone and a lubricant and then performing melt extrusion to obtain a melt.

[0028] In this invention, the polyphenylene sulfone is preferably polyphenylene sulfone chips; the melt index of the polyphenylene sulfone at 360°C and 5kg is preferably 20-25g / 10min.

[0029] In this invention, the lubricant is preferably 0.05-0.1% of the mass of polyphenylsulfone; the lubricant is preferably a metal stearate compound, more preferably magnesium stearate, zinc stearate, or calcium stearate. The use of a lubricant in this invention can improve the melt flowability and extrusion stability.

[0030] The present invention does not have any special limitations on the operation of mixing the polyphenylsulfone and the lubricant, and any technical solution for preparing the mixture well known to those skilled in the art can be used.

[0031] In this invention, the mixed material is preferably dried before melt extrusion; the drying temperature is preferably 150°C; and the drying time is preferably >6 hours. This invention utilizes drying to remove moisture, ensuring that the moisture content of the polyphenylsulfone chips is below 50 ppm, thereby reducing degradation caused by high-temperature extrusion.

[0032] In this invention, the temperature of the melt extrusion is preferably 360–380°C, more preferably 365–375°C; the melt extrusion is preferably carried out in a high-temperature melt extruder. This invention does not have a specific limitation on the model of the high-temperature melt extruder; any instrument or equipment well-known to those skilled in the art can be used.

[0033] In this invention, the screw pressure during melt extrusion is preferably 8–12 MPa, more preferably 10 MPa; the screw rotation speed is preferably 30–50 r / min. This invention increases shear force and improves melt flowability by controlling the screw pressure and rotation speed.

[0034] After obtaining the melt, the present invention extrudes the melt through a spinneret to obtain nascent monofilaments.

[0035] The present invention does not have a specific limitation on the model of the spinneret; any instrument or equipment familiar to those skilled in the art can be used.

[0036] The present invention does not have any special limitations on the operation of the melt being extruded through the spinneret; any operation known to those skilled in the art can be used.

[0037] After obtaining the nascent monofilament, this invention sequentially subjectes the nascent monofilament to oil bath cooling, drawing, and winding to obtain a cooled and shaped nascent monofilament. The oil bath cooling method used in this invention improves the surface smoothness of the nascent monofilament after cooling, which is beneficial for subsequent drawing.

[0038] In this invention, the oil bath cooling temperature is preferably 40–50°C; the oil bath cooling time is preferably 5–10 seconds; and the oil bath cooling medium is preferably any one of silicone oil, triethylene glycol, and glycerin. This invention uses an oil bath for rapid cooling. Due to the high boiling point of oil, the nascent monofilament is less likely to instantly boil and vaporize upon entering the cooling oil, thus avoiding the impact on the monofilament surface and preventing the formation of rough, fish-scale-like patterns. If water is used as the cooling medium, the monofilament surface will be very rough, making subsequent drawing impossible.

[0039] The present invention does not impose any special limitations on the traction and winding operations; operations familiar to those skilled in the art can be used.

[0040] After obtaining the cooled and shaped nascent monofilament, the present invention sequentially performs slow drawing and heat setting on the cooled and shaped nascent monofilament to obtain large-diameter polyphenylsulfone monofilament. The present invention uses slow drawing, which can achieve slow cold drawing of nascent monofilament, not only enabling molecular chain orientation but also avoiding filament breakage, thereby obtaining large-diameter polyphenylsulfone monofilament.

[0041] In this invention, it is preferable to place the cooled and formed nascent monofilament onto a decoupling frame before the slow drawing process, and then place the decoupling frame at the front end of the drawing machine. This invention does not impose any special limitations on the above operations; any operations well-known to those skilled in the art can be used. Placing the cooled and formed nascent monofilament onto the decoupling frame and then placing the decoupling frame at the front end of the drawing machine facilitates subsequent slow drawing.

[0042] In this invention, the slow drafting is preferably performed in a drafting machine; rubber pressure rollers are preferably provided before and after the drafting machine. This invention does not have a specific limitation on the model of the drafting machine; any instrument or equipment well-known to those skilled in the art can be used. The rubber pressure rollers provided before and after the drafting machine in this invention can prevent slippage and control the drafting point.

[0043] In this invention, the slow drawing speed is 3-5 m / min, preferably 3-4 m / min; the multiple of the slow drawing speed is preferably 1.5-1.7 times, more preferably 1.6-1.7 times. The strength of the monofilament in this invention mainly depends on the orientation degree of the polymer's amorphous molecular chains. Therefore, the higher the drawing multiple, the better the molecular chain orientation, the greater the strength of the monofilament, and the smaller the elongation at break. To obtain PPSU monofilaments with a certain strength, the nascent monofilaments need to be drawn. The purpose of drawing is to orient the polymer molecular chains. However, PPSU, as an amorphous polymer, softens directly when heated above its glass transition temperature, resulting in monofilaments with no strength that break easily. If the temperature is below the glass transition temperature, the stress is too high during high-speed drawing, leading to stress whitening and easy breakage, making continuous production impossible. This invention involves slow cold drawing of nascent PPSU monofilaments at room temperature. The cold drawing ratio is controlled to be 1.5 to 1.7 times the ratio at which the monofilaments are just fully necked or slightly necked. This yields monofilaments with a strength of 1.2 to 1.5 cN / dtex and an elongation at break of 20 to 30%.

[0044] In this invention, the heat setting temperature is preferably no more than 220°C; the heat setting time is preferably 50–80 seconds; and the heat setting is preferably performed in a hot air box. This invention does not have a specific limitation on the type of hot air box; any instrument or equipment well-known to those skilled in the art can be used. The heat setting method used in this invention can eliminate internal stress and improve the dimensional stability of the monofilament.

[0045] After heat setting, the present invention preferably winds up the heat-set monofilament to obtain a large-diameter polyphenylsulfone monofilament.

[0046] The present invention does not impose any special limitations on the winding operation; any operation known to those skilled in the art can be used.

[0047] The addition of lubricant in this invention can improve the flowability and extrusion stability of polyphenylsulfone, and avoid melt fracture during extrusion. The subsequent oil bath cooling can improve the surface smoothness of the nascent monofilament after cooling, which is beneficial to subsequent drawing. The use of slow drawing speed can realize the slow cold drawing of the nascent monofilament, which can not only orient the molecular chain, but also avoid filament breakage, thereby obtaining large-diameter polyphenylsulfone monofilament.

[0048] This invention uses a high-temperature melt spinning method to produce PPSU nascent monofilaments, which are then slowly cold-drawn and heat-set at room temperature to obtain large-diameter monofilaments. The diameter of the monofilaments can be controlled between 0.08 and 1.2 mm.

[0049] The present invention also provides a large-diameter polyphenylsulfone monofilament prepared by the preparation method described in the above technical solution.

[0050] The large-diameter polyphenylsulfone monofilament provided by this invention has excellent mechanical properties, with a diameter in the range of 0.08 to 1.2 mm.

[0051] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0052] Example 1

[0053] A method for preparing large-diameter polyphenylsulfone monofilaments comprises the following steps:

[0054] (1) Calcium stearate was added to PPSU chips with a melt index of 20 g / 10 min (360℃ / 5 kg) and dried in a vacuum rotary kiln at 150℃ for 6.5 h to make the moisture content of the chips less than 50 ppm. Then, the chips were melt extruded using a high-temperature melt extruder to obtain the melt. The mass of calcium stearate was 0.1% of the mass of the PPSU chips. The extrusion temperature was 378℃, the screw pressure was 10 MPa, and the screw speed was 40 r / min.

[0055] (2) The melt obtained in step (1) is extruded through a spinneret to obtain a nascent monofilament;

[0056] (3) The nascent monofilament obtained in step (2) is rapidly cooled in an oil bath at 40°C for 6 seconds, and then directly wound into a spool after being pulled by a traction roller to obtain a cooled and shaped nascent monofilament with a diameter of 0.20 mm; wherein, the medium of the oil bath is triethylene glycol with a purity of more than 95%;

[0057] (4) The spool of the cooled and formed nascent monofilament obtained in step (3) is placed on the unwinding frame, and then the unwinding frame is placed at the front end of the seven-roll drawing machine. Under the action of the drawing machine's traction force, the nascent monofilament is unwound from the spool of the unwinding frame at a uniform speed, and then slowly drawn through two sets of seven-roll drawing machines spaced 4m apart. The drawn monofilament is then heat-set in a hot air box with a length of 4m, and finally wound into the spool to obtain a large-diameter polyphenylsulfone monofilament with a diameter of 0.163mm. Rubber pressure rollers are set at the front and rear of the drawing machine. The slow drawing speed is 5m / min, and the drawing speed ratio is 1.5 times. The heat setting temperature is 180℃, and the heat setting time is 50s.

[0058] The polyphenylene sulfone monofilament prepared in Example 1 was tested using an electronic single-yarn tensile testing machine. The clamping distance was set to 500 mm and the tensile speed to 500 mm / min. The monofilament was fixed at both ends of the pneumatic clamp, and the tensile testing machine was started to stretch it until it broke. The tensile testing machine automatically returned to the initial clamping distance. The computer software automatically calculated and displayed the breaking strength and elongation at break of the monofilament. The strength was 1.25 cN / dtex and the elongation at break was 28%.

[0059] Example 2

[0060] A method for preparing large-diameter polyphenylsulfone monofilaments comprises the following steps:

[0061] (1) Calcium stearate was added to PPSU chips with a melt index of 22 g / 10 min (360℃ / 5 kg) and dried in a vacuum rotary kiln at 150℃ for 7 h to make the moisture content of the chips less than 50 ppm. Then, the chips were melt extruded using a high-temperature melt extruder to obtain the melt. The mass of calcium stearate was 0.1% of the mass of the PPSU chips. The extrusion temperature was 375℃, the screw pressure was 10 MPa, and the screw speed was 38 r / min.

[0062] (2) The melt obtained in step (1) is extruded through a spinneret to obtain a nascent monofilament;

[0063] (3) The nascent monofilament obtained in step (2) is rapidly cooled in an oil bath at 40°C for 7 seconds, and then directly wound into a spool after being pulled by a traction roller to obtain a cooled and shaped nascent monofilament with a diameter of 0.50 mm; wherein the medium of the oil bath is triethylene glycol with a purity of more than 95%.

[0064] (4) The spool of the cooled and formed nascent monofilament obtained in step (3) is placed on the unwinding frame, and then the unwinding frame is placed at the front end of the seven-roll drawing machine. Under the action of the drawing machine's traction force, the nascent monofilament is unwound from the spool of the unwinding frame at a uniform speed, and then slowly drawn through two sets of seven-roll drawing machines spaced 4m apart. The drawn monofilament is then heat-set in a hot air box with a length of 4m, and finally wound onto the spool to obtain a large-diameter polyphenylsulfone monofilament with a diameter of 0.395mm. Rubber pressure rollers are set at the front and rear of the drawing machine. The slow drawing speed is 4m / min, and the drawing speed ratio is 1.6 times. The heat setting temperature is 200℃, and the heat setting time is 60s.

[0065] The polyphenylsulfone monofilament prepared in Example 2 was tested using an electronic single-yarn tensile testing machine. The clamping distance was set to 500 mm and the tensile speed to 500 mm / min. The monofilament was fixed at both ends of the pneumatic clamp, and the tensile testing machine was started to stretch it until it broke. The tensile testing machine automatically returned to the initial clamping distance. The computer software automatically calculated and displayed the breaking strength and elongation at break of the monofilament. The strength was 1.35 cN / dtex and the elongation at break was 25%.

[0066] Example 3

[0067] A method for preparing large-diameter polyphenylsulfone monofilaments comprises the following steps:

[0068] (1) Calcium stearate was added to PPSU chips with a melt index of 25 g / 10 min (360℃ / 5 kg) and dried in a vacuum rotary kiln at 150℃ for 7.5 h to make the moisture content of the chips less than 50 ppm. Then, the chips were melt extruded using a high-temperature melt extruder to obtain the melt. The mass of calcium stearate was 0.1% of the mass of the PPSU chips. The extrusion temperature was 372℃, the screw pressure was 10 MPa, and the screw speed was 40 r / min.

[0069] (2) The melt obtained in step (1) is extruded through a spinneret to obtain a nascent monofilament;

[0070] (3) The nascent monofilament obtained in step (2) is rapidly cooled in an oil bath at 40°C for 10 seconds, and then directly wound into a spool after being pulled by a traction roller to obtain a cooled and shaped nascent monofilament with a diameter of 0.90 mm; wherein the medium of the oil bath is triethylene glycol with a purity of 95% or higher.

[0071] (4) The spool of the cooled and formed nascent monofilament obtained in step (3) is placed on the unwinding frame, and then the unwinding frame is placed at the front end of the seven-roll drawing machine. Under the action of the drawing machine's traction force, the nascent monofilament is unwound from the spool of the unwinding frame at a uniform speed, and then slowly drawn through two sets of seven-roll drawing machines spaced 4m apart. The drawn monofilament is then heat-set in a hot air box with a length of 4m, and finally wound into the spool to obtain a large-diameter polyphenylsulfone monofilament with a diameter of 0.69mm. Rubber pressure rollers are set at the front and rear of the drawing machine. The slow drawing speed is 3m / min, and the drawing speed ratio is 1.7 times. The heat setting temperature is 215℃, and the heat setting time is 80s.

[0072] The polyphenylsulfone monofilament prepared in Example 3 was tested using an electronic single-yarn tensile testing machine. The clamping distance was set to 500 mm and the tensile speed to 500 mm / min. The monofilament was fixed at both ends of the pneumatic clamp, and the tensile testing machine was started to stretch it until it broke. The tensile testing machine automatically returned to the initial clamping distance. The computer software automatically calculated and displayed the breaking strength and elongation at break of the monofilament. The strength was 1.5 cN / dtex and the elongation at break was 20%.

[0073] As can be seen from the above embodiments, the preparation method provided by the present invention can prepare large-diameter polyphenylsulfone monofilaments, and the monofilaments have high strength and high elongation at break.

[0074] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing large-diameter polyphenylsulfone monofilaments, comprising the following steps: (1) Polyphenylsulfone and lubricant are mixed and then melt-extruded to obtain a melt; the lubricant is magnesium stearate, zinc stearate or calcium stearate; (2) The melt obtained in step (1) is extruded through a spinneret to obtain a nascent monofilament; (3) The nascent monofilaments obtained in step (2) are sequentially subjected to oil bath cooling, traction and winding to obtain cooled and shaped nascent monofilaments; (4) The nascent monofilaments obtained in step (3) are subjected to slow stretching and heat setting in sequence to obtain large-diameter polyphenylsulfone monofilaments; the slow stretching speed is 3~5m / min; In step (3), the medium for oil bath cooling is either silicone oil or triethylene glycol.

2. The preparation method according to claim 1, characterized in that, In step (1), the melt index of polyphenylsulfone at 360℃ and 5kg is 20~25g / 10min.

3. The preparation method according to claim 1, characterized in that, In step (1), the mass of the lubricant is 0.05 to 0.1% of the mass of polyphenylsulfone.

4. The preparation method according to claim 1, characterized in that, The temperature of melt extrusion in step (1) is 360~380℃.

5. The preparation method according to claim 1 or 4, characterized in that, In step (1), the screw pressure during melt extrusion is 8~12MPa, and the screw rotation speed is 30~50r / min.

6. The preparation method according to claim 1, characterized in that, In step (3), the temperature of the oil bath cooling is 40~50℃, and the oil bath cooling time is 5~10s.

7. The preparation method according to claim 1, characterized in that, In step (4), the speed of slow stretching is 1.5 to 1.7 times.

8. The preparation method according to claim 1, characterized in that, In step (4), the heat setting temperature shall not exceed 220°C and the heat setting time shall be 50~80s.

9. Large-diameter polyphenylsulfone monofilaments prepared by the preparation method according to any one of claims 1 to 8.